Controlling mechanism



F. D. HOLDSWORTH CONTROLLING MECHANISM Filed July 6, 1920 Patented Nov. d, i923.

TTS @FFE Ldlthtitll FRED HOLDSWGRTH, OF CLARE'MONT, NEW HAMPSHIRE, @SKG-NOB T0 ULLNMCT MACHINERY COMPANY, A CORPORTION OF MASSACHUIETTS.

CN'TROLLNG MECHANISM.

To all whom 'it may concern Be it known that l, FRED l). HoLDswORTH, a citizen of the UnitedStates vresiding at Claremont, in the county of State of New Hampshire, have invented certain new and useful Improvements in Controlling Mechanisins, of which the following is a full, clear, and exact specification.

My invention relates to controlling mechanisms and more particularly to compressor Acontrolling mechanisms.

An object oi my invention is to provide an improved compressor controlling means. Another object of m-y invention is to provide an improved controlling mechanism for motor driven compressors of the type wherein the motor is stopped and started and the compressor loaded and unloaded in accordance with variations in compressor discharge or receiver preure. Further objects of my invention will appear in the course of the following speciication and claims.

lin the accompanying drawings l have shown for purposes of illustration, one form which iny invention may assume in practice.

Fig. 1 is a side elevation of a compressor system p-rovided with my improved controlling mechanism, a portion of the compressor cylinder being broken away to show the inlet valve mechanism.

Fig. 2 is a central vertical section through the control mechanism which li have used as an illustrative embodiment o my invention. V

Fig. 3 is a detail sectional view on an enlarged scale of the pilot switch.

- l have shown my improved compressor controlling mechanism in combination with a compressor-system comprising a compressor 1 having a cylinder 2, discharge mechanism generally indicated by 3, and inlet mechanism generally indicated by 4 and which will be more fully described later. The compressor 1 is driven by a motor 5 which is supplied with current through mains 6 and 7 under control of a switch 8 which is of the magnet controlled type, being controlled by the magnet 9, and the latter is controlled by mechanism which will be described hereafter. The compressor inlet mechanism consists of a plurality of inlet valves 1() of which but one is shown, these valves being provided with stems 1l and being normallyfdullivan and `hold it at the top of its each held closed by a spring l2 which is ot' such strength as to be overcome by the suction produced by the movement of the piston on the suction stroke. For the purpose of unloading the compressor, lungersl 13 are provided in cylinders 14, hese plun ers, when subjected to fluid pressure on t eir lower sides, tend to raise the valves 10 and accordingly maintain them open where by the air is permitted to pump into and out of the cylinder as the piston reciprocates. Fluid pressure is supplied to and conducted away from the cylinders 14 by piping 15 which is under the control of my improved mechanism the details of which will now be described.

For the purpose of controlling both the operation of the motor 5 and the position of the inlet valves, l have rovided the controlling mechanism which is most clearly illustrated in Fi 2. This mechanism comprises a cylin er 16 in which a piston 17 is reciprocable, the piston being subjected to the action of the springs 18 which normally cr linder 16, and being adapted to be movedy downward by fluid pressure transmitted to the top of the chamber 16-by way of a port 19. At this point attention is directed to the fact that a large clearance volume is provided as indicated at 20 at the top of the chamberlt, the purpose of this clearance volume being` to provide a considerable quantity oi air in the cylinder, which air will take a considerable time to exhaust, as later described. The port 19 is controlled by the check valve 2l. and the check valve 21 is provided with a central vent of small size as indicated at 21. Fluid pressure is supplied to the clieclr valve, which opens toward the cylinder 16, by way of the connection 22 and the latter is controlled by means of a well known type of pilot valve, here shown as the f Judson type. Thispilot valve, which is designated 23, has a connection 24 with the receiver 25 which receives the discharge from the oompressor cylinder 2, and is also provided with a small exhaust port 26. The o eration of the pilot valve, as is well known, 1s' such that upon rise of receiver pressure above a desired limit, the pilot valve will open and transmit pressure through the connection 22 while closing the exhaust 2d When, however, the pressure falls below a certain slightly lower desired limit, the pilot valve liti lil?! ies will close the communication between the connections 24 and 22 and will place the connection 22 in communication withthe exhaust 26, thereby placing the cylinder 16 in communication with the atmosphere. It will thus be seen that the piston 17 will move downwardly at such time as fluid pressure in the receiver exceeds a predetermined desired amount, and will move backward at a retarded rate due to the necessity of fluid pressure escaping from above it by way of the vent 21 in the check valve 21 upon the falling of the pressure within the receiver below a predetermined 'desired limit. The piston 17 is provided with a projecting rod 27 which carries 'at its lower end a cross head 28, to a portion of which the springs 18 are attached, and this cross head is guided as at 29. At the bottom end of the cross head member is an adjustable contact element 3() which is in turn adapted to impinge upon a pin 31 which controls a switch 32 of a, well known type, the switch 32 being soarranged at the lower end of the guide member 29 as to have its control pin 31 impinged bv the contact member 30 when the piston 17 reaches substantially' the bottom end of its stroke. The switch 32 is so constructed that when the member 31 is forced downwardly the circuit 33 which controls the magnet 9 is opened, thereby causing the opening of the main circuit through the motor 5; and upon release of the plunger 31 by upward movement of the piston, the circuit 33 through the solenoid 9 is at once closed in such a manner that the motor resumes operation.

The mechanism for controlling the operation of the inlet valves and so the unloading of the compressor, is generally designated by the numeral 34. A fluid connection 35 leads oil from the receiver line 24 and enters a valve casing 36 within which is reciprocable a valve member 37 having seating portions 38 and 39 respectively at its upper and lower ends. This valve is designed to control the communication through a port 40 between the ipe 15 and either the receiver orthe atmosp ere, and when in its upper position, it opens an exhaust through a passage 42 to the atmosphere, the seating portion 39 at that time being raised from its seat and the pressure being free to pass out around the guiding portions 43 of the valve and so to the passage 42. When the valve is in its opposite position, the seating portion 39 will close the exhaust 42 and fluid pressure from line 35 will low to pipe 15. It will be noted that due to the fluid pressure always within the pipe 35, the valve is given a bias to the position last described. For the purpose of raising the valve to open the exhaust and close the connection 35, I have pivoted a spring member of relatively strong, but elastic, sheet metal at a point end of the plunger27 and rests thereon.- in' such manner as to be raised by u ward movement of the piston 17. It will obvious that due to the leverage providedl by the arrangement of the spring 45 the plunger 46 will b e subjected to a considerable pressure when the piston 17 is in its upper position. When, however, the piston 17 is at the lower end of its stroke, the spring 45 is free to swing downwardly and rest upon a web member 47 and the plunger 46 having been freed, the valve member 37 moves downwardly, closing the exhaust 42 and opening communication between the lines 35 and 15, thereby raising the plungers 13 and unloading the compressor.

From the foregoing description, the operation of my device will readily be apparent. Upon rise of pressure in the receiver above a predetermined desired amount, the pilot valve 23 will close the exhaust 26 and open communication between the line 24 and the top of the cylinder 16. There will accordingly occur a. downward movement of thepiston 17 and a resultant/releasing of the plunger 46 with the consequentl opening of the valve 37 in such manner as to permit supply of fluid through pipes 35 and 15 to unload the compressor, and also the impact of the contact member 30 upon the plunger 31 will cause a breakin of the solenoid circuit and so of the maln circuit leading to the motor 5. Consequently, the compressor will be both unloaded and no longer in operation. When the pressure in the receiver falls to the desired degree, the pilot valve 23 will operate to close the communication between passages 24 and 22 and will place the passage 22 in communication with the exhaust port 26. The fluid within the top ofthe cylinder 16 and in the clearance chamber 20 will accordingly flow out by way of vent port 21 and exhaust port 26 as rapidly as this can be accomplished through a port of the size provided. Slow upward movement of the piston will accordingl occur due to the springs 18, and a relative y small movement will suffice to release the in 31 and permit restarting of the motor. y the time that suicient pressure has escaped from the top of the cylinder 16 to permit the member 28 to pick up the lever 45 and move the valve 37 to close communication between lines 35 and 15 and open communication between line 15 and the exhaust 42, the motor will be at full speed and accordingly the loading of the compressor, due to release of the pressure beneath the plungers 13, will take place after the motor has reached full speed. Owing to the resilience of the lever 45, the movement of the valve wlll be very-sharp and it will snap from its Teo ilo

lower seat to its upper seat. From the foregoing description, 1t will be obvious that I have provided means for unloading the compressor and stopping the motor substantially simultaneously, and for also efecting starting of the motor and the brinfring of it up to speed prior to the loading ofiD the compressor. The sgging connection between the actuating mem r and the compressor unloading mechanism control valve is such that very accurate proportioning of the parts is notrequisite, and yet positiveness of o eration lis obtained.

hile I have in this application specifically described one form which my invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is 1. In a compressor controlling mechanism, in combination, a compressor` unloading means, a controlling valve therefor, a iexible lever for actuating the latter, and means movable in consequence of compressor discharge pressure variations to move said lever and adapted indifferent positions to pick up said lever and flex the same against said valve means and to move out of contact with said lever entirely.

2. In a compressor controlling mechanism, in combination, a compressor unloading means, a control valve therefor, a lever of the second class for actuating the latter, means for controlling the running of the compressor, and means movable in consequence of compressor discharge pressure variations normally contacting with the free end of said lever and engagable with said second mentioned means to control the latter.

3. In a compressor controlling mechanism, in combination, a compressor unloading means, a controlling valve therefor comprisng a reciprocatory valve, means for controlling the running of the compressor comprising an element reciprocable in a path parallel to the path of said valve, a cylinder, the axis of which is parallel to the path of movement of said valve, a piston in said cylinder movable in a path parallel to the path of said valve, means for effecting reciprocation of said piston in consequence of receiver discharge pressure variations, and a lever of the second class for actuating said valve `o perated by said piston, said piston in its -'reciprocation,also controlling said element.

4. In combinatin, in a compressor system comprising""a" compressor, a driving motor therefor and a receiver, compressor controlling mechanism comprising a motor controlling switch, controlling means therefor, compressor unloading means, controlling means therefor, a lever for actuating the latter, land a reciprocatory member alternately contacting with said lever and with the controlling means for said motor controlling switch.

5. In combination, in a compressor system comprising a compressor, a driving motor therefor and a receiver, compressor controlling mechanism comprising a motor controlling switch with controlling means therefor, compressor unloading means with controlling means therefor, a lever for actuating the latter, a reciprocatory member alternately contacting with the lever and with the controlling means for said motor controlling switch, and means for supporting said lever in position for engagement by said reciprocatory member.

6. In combination, in a compressor system comprising a compressor, a driving motor therefor and a receiver, compressor controlling mechanism comprising a motor controlling switch, controlling means therefor, compressor unloading mea-ns, controlling means therefor, a lever for actuating the latter, and a reciprocatory member alternately contacting with said lever and with the controllingmeans for said motor controlling switch, said reciprocatory member being movable in Aresponse to receiver pressure lvariations.

In testimony whereof I aiix my signature. 

